All the best to both of you, @GavinCh - most of us find that after the actual surgery, a HUGE weight is lifted off our shoulders - and the recuperation isn't as bad as our minds have built it up! Once the Pathology results are back, you'll both have a clear idea of the followup treatment.
Yep, keeping busy in the mean time is the way to go. Maybe see if you/Karen can cook up a few meals for the freezer as she may have limited arm movement for a little while afterwards.
Re preparing for hospital - a few things that helped me get thru it was my iPad with charger (for messages & amusement), my eye mask (as from airlines) and ear plugs were a god send (hospitals are noisy places with lights on all the time!) A few magazines (short stories) rather than books. Maybe some treats (biscuits/lollies.) A warm top (hospitals can be cold places too.) A front opening nightie (for ease of putting on/off and also for Surgeon's inspection the next day.) Don't forget to take any 'regular medications' with you that Karen may be on as well. Let the nursing staff know what she needs to take.
Take care xx